The two choices are the Sony HVL-f32X or the Metz 54MZ (the adapter for the hot shoe is being developed in Germany even as I write this). It's been years since I was "into" photography until I decided to go digital with the Sony 828, and the specs are all rather mind boggling after being "out" of photography for many years.

I'm up to speed with the 828 now, and want a more powerful flash that is fully compatible with the camera. (in my ignorance I'm thinking the Metz unit is "fully" compatible, I could be wrong.)

Please tell me which you'd choose and why. Are there others that would be fully compatible with the Sony that I'm not considering?

TTL is the acronym for "Through The Lens". The Sony HVL-F32x flash unit fires a pre-flash and the camera reads this flash to determine how much light to discharge for the exposure. There's quite a bit going onduringthat, and the two units work nicely together. There are two other modes that the flash can work in. In one, the flash itself reads the correct exposure, and the second is manual where you figure out the exposure. Most times (so far) I let the camera do the work.

FWIW, I went with the Sony flash and haven't regretted it. It took quite awhile for Sony to send it however. Don't be surprised if they don't send it for 3 weeks.

If you registered (or will register now) your F828, Sony Style will discountthe purchase and then some. The other good price I found (better than the discounted Sony Style price) was at CDW.

I'm using the Metz 54 MZ-4 with the SCA adapter available for the DSC-V1. It works ok for me with the DSC-F828. The Metz SCA system communicates with the 828 so they work nicely. Even the flash unit turn on the camera automatically.

The Metz system doesn't support pre-flash with Sony cameras to date, so I can't use the TTL mode. Only the full auto and manual modes are available. Even in full auto mode you can use flash compensation form the camera menu and/or from the flash unit.

Also I can take advantage of the zoom feature of the flash, the second light for bounced flash and the ability to use the same unit with Nikon, Canon and other cameras in dedicated flash mode changing the SCA adaptor.

Quite expensive, worth the price if you a powerfull flash for serious work.